Cataracts in Dogs and Cats

by Nancy Kay, DVM

While cataracts are less common in dogs and cats than in people, they do occur with relative frequency and are one of the most common causes of blindness. Normally, the pupil of the eye appears black because the lens (located just behind the iris) is crystal clear. A cataract is an opacification within the lens, and when a cataract is “mature” it imparts a grayish, whitish color to the pupil. The opacification prevents normal light transmission to the retina within the back of the eye. A fully opacified lens (a mature cataract) results in blindness.

Some dog breeds are genetically predisposed to cataract formation including: American Cocker Spaniel, Bichon Frise, Australian Shepherd, Miniature Schnauzer, Siberian Husky, Boston Terrier, Labrador Retriever, Golden Retriever, Lhasa Apso, and all varieties of Poodles. Diabetes mellitus and diseases within the eye (inflammation, glaucoma, displacement of the lens) can also cause cataract formation.

The treatment of choice for mature cataracts (those resulting in blindness) is surgical removal of the affected lens(es). This is a delicate procedure, one that should be performed only by a veterinarian who is a specialist in veterinary ophthalmology. Prior to surgery, special testing is performed to insure the retinas are working normally. (If the retina is diseased, removal of the cataract will not restore vision). During surgery, ultrasound is used to break up or emulsify the cataract. The lens material is then aspirated from the eye through a tiny incision. A new lens can then be inserted within the remaining lens capsule to restore normal post-operative vision.

Cataracts typically form gradually, giving the dog or cat time to adapt to their vision loss. While it is tempting to assume that a blind animal’s quality of life would be vastly diminished, rarely is this the case. They are masters at using their other senses to navigate their environment. My point being, there is no reason to despair if cataract surgery is not a feasible option for your blind pet.

Do you have the sense that your best buddy’s pupils are not as black as they used to be? Don’t assume that he or she has cataracts. Lenticular sclerosis is a normal aging process that causes the pupils to appear grayish or cloudy. In fact, this change is evident in most dogs and cats over the age of ten. The good news is that lenticular sclerosis does not interfere with light transmission to the retinas. In other words, this “normal abnormality” does not affect vision and does not require any therapy. Your veterinarian will be able to determine if your pet has cataracts or lenticular sclerosis by performing a thorough eye examination.

Dr. Nancy Kay, DVM Diplomate, American College of Veterinary Internal Medicine.
Recipient, American Animal Hospital Association 2009 Animal Welfare and Humane Ethics Award Recipient, 2009 Dog Writers Association of America Award for Best Blog Recipient, 2009 Eukanuba Canine Health Award

Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
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